1. Field of the Invention
Embodiments of the present invention relate generally to scanning probe microscopes and, more particularly, to scanning probe microscope that is capable of compensating for drift.
2. Description of the Related Art
Scanning probe microscopes (SPMs) provide microscopic analysis of the topography or other characteristics of microscopic surfaces and are powerful instruments for the study of nanometer-scale features. SPMs include devices such as scanning force or atomic force microscopes (SFMs or AFMs), scanning tunneling microscopes (STMs), scanning acoustic microscopes, scanning capacitance microscopes, magnetic force microscopes, scanning thermal microscopes, scanning optical microscopes, and scanning ion-conductive microscopes. Generally, SPMs are a class of instruments that employ a technique of mapping the spatial distribution of a surface property of a sample by localizing the influence of the property to a small probe positioned in very close proximity to the sample surface. The probe moves relative to the sample and either measures the change in the property or follows constant contours of the property, and an image is typically formed by scanning the sample with respect to the probe in a raster pattern and recording data at successive points in the scan. Depending on the type of SPM, the scanning probe either contacts or rides slightly above the surface to be analyzed, e.g., on the order of a few hundred angstroms. In either case, resolution of the surface property is achievable on the nanometer scale.
One issue known to affect the accuracy of SPM measurements is drift, which is the positioning error caused by changes in relative position between a sample and a scanning probe. Drift in SPMs results from thermal and mechanical displacements that occur over a period of time. Sources of drift include vibration, hysteresis, expansion and contraction of SPM structures due to small temperature changes, and other factors. Because the probe and sample in an SPM have to be controlled to the accuracy of sub-nanometers, even very subtle external factors may contribute significantly to drift.
Because positioning errors in an SPM between the probe and the sample directly affect the performance of the SPM, and because minimizing each and every significant source of drift in an SPM is problematic if not impossible, there is a need in the art for a system and method to reduce the effect of drift on the performance of SPMs.